This character engages in Polygamy.
Polygamy is a marriage which includes more than two partners.
When a man is married to more than one wife at a time, the relationship is called polygyny, and there is no marriage bond between the wives; and when a woman is married to more than one husband at a time, it is called polyandry, and there is no marriage bond between the husbands. If a marriage includes multiple husbands and wives, it can be called group marriage.
Compare polyamory, which does not require partners to be married.